Filter circuits that provide stop band attenuation are well-known. On such type of circuit is a notch circuit, that filters frequencies from a certain portion of the frequency spectrum (corresponding to the notch), and allows other frequencies to pass. FIGS. 1(a) 1-2 and 1(b) 1-2 illustrate a conventional prior art C-R-C and C-L-C low pass filtering circuits, respectively, as well as their respective performance characteristics. As shown, they provide a stop band at about 800 MHz to 6 GHz, which covers the radio frequency range used for wireless communication. A steep roll off from pass band to stop band frequency is highly desired, especially when high speed signals are incorporated in these devices.
The present invention a circuit that provides desired stop-band performance in smaller areas, as well as less attenuation of the lower frequencies that are desired.